Everything You Ever Wanted To Know About Tesla Batteries

You have questions, Two Bit da Vinci has answers.

One of the main reasons Tesla is where it is today is because of batteries. They attacked the problem of electric vehicle range — the traditional weak point of EVs — by choosing the most energy-dense cell available and then developed the battery pack to suit its needs. The result was a more than 200 miles of range and all the power needed to not only turn heads, but to turn an entire industry on its ear.

Now, there’s a lot to lithium batteries and they’ve been changing over time. If you’re like us, you probably have a few questions about the batteries in assorted Tesla vehicles but haven’t had the opportunity to ask. Well, today might be our lucky day as Two Bit da Vinci rides to the rescue with Part one of a two-part series that will very likely answer our questions. All you need is about a dozen minutes, so if you’ve got that, sit back and hit play on the video above. Enjoy!

Today we are going to talk about “The Truth about Tesla’s Batteries.” If you’re thinking about a Tesla, you’ve undoubtedly heard about how cheap they are to fill up, how little maintenance they require, and with recent Model 3 Production ramp ups, we’re on the verge of absolute Tesla ubiquity. But one of the questions that we believe keep potential buyers up at night, surrounds their battery packs. So we’ve compiled a list of all the questions we’ve received, and we’re going to break it down, step by step in this two part video series.

First we’ll look at the raw materials required to create lithium ion batteries. Second we’ll look at the battery cell manufacturing. In part 2, we’ll look at the complete battery pack manufacturing, the final Car manufacturing, and end of life recycling of lithium ion batteries.

Different car makers use different cathode chemistries for lithium ion batteries, Tesla uses NCA chemistry, or Nickel, Cobalt, and Aluminium (LiNiCoAlO2). They use this particular chemistry because it offers great energy density, long cycle life, and great charge performance. This makes Tesla’s batteries the absolute top of the line in the EV world. They weigh less, last longer, and power the performance of things like Ludicrous mode.

Tesla’s Batteries have gone through 3 stages: Stage 1 was from 2009-2012 found in the Roadster and Model S. Stage 2 was from 2016-2018 and powered the Model S Gen II, and the Model X. Stage 3 starts with the Model 3 in 2018.

Stage 1 batteries were constructed with 18650 cells, which are 18 mm wide, and 65 mm tall. They had a NCA formulation that required 11kgs of Cobalt in the cathode, per car. They had a pure graphite anode, with no Silicon.

Stage 2 batteries used the same 18650 cells, but reduced the amount of Cobalt required in the cathode from 11 to just 7kg/car. They also introduced a small amount of silicon into their anode.

Stage 3 batteries are new for Tesla, and first shipped with the Model 3. Stage 3 batteries have further reduced the amount of cobalt to just around 4.5kg per vehicle. They also have a hybrid silicon/graphite anode, and while proprietary and unreported, probably higher silicon content than their stage 2 batteries.

Unlike other companies that are planning to sell tens of thousands of EVs each year, Tesla is planning to sell half a million and then a million EVs each year. It’s absolutely crucial to understand supply chain fragility when considering that lithium ion battery production is set to soar. Tesla opened Gigafactory 1 in Sparks Nevada, and though it will only be fully completed by 2020, its pumping out batteries, and will only increase its production rate as it nears completion. Tesla has switched from 18650 cells to 21700 cells because it’s an optimized size to maximize energy, with minimal increases in weight, and excellent cost. Voltage is largely unchanged, since its a function of battery chemistry. So the big question here is, why does Tesla use these little battery cells, when they know they’ll need thousands of them? Why not not make custom big batteries, like the ones found on a BMW i3? The i3 uses prismatic batteries, with big custom packs. The Chevy bolt and Leaf use rectangular pouch batteries, which you might think makes more sense since there’s less wasted space.

The i3’s prismatic battery and the Bolts pouch battery have to be specifically made for those cars. They are built to specification, much like your smartphone. Figure out how much space you have left for a battery, then get one custom made. In contrast, the Tesla model 3 uses a new 2170 cell which will be the battery that powers all future tesla models and even their home energy storage solutions.

This flexibility is why Tesla can offer a wide variety of range options. By adding more cell blocks in parallel they can increase range without changing the core voltage of the system. Tesla has a goal of producing batteries at less than $100/kWh.

The Gigafactory is Tesla’s greatest asset, because by investing so heavily into a vertical integration structure, they can control costs and production levels. In contrast General Motors, completely outsources the battery development to LG Chem, who provide complete units ready to drop into their EVs. But if suddenly Honda and Toyota come with contracts to LG Chem, how would that impact GM? Vertical integration for battery manufacture is super costly, but does give Tesla a marked advantage over their competition. In fact, it might be their single biggest advantage.

One question we often get is who’s actually making the battery, Panasonic or Tesla? The answer really is Panasonic. It takes decades to master the chemistry of Batteries, and that’s where Panasonic comes in.

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22 Comments on "Everything You Ever Wanted To Know About Tesla Batteries"

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HVACman

from the video: “The i3’s prismatic battery and the Bolts pouch battery have to be specifically made for those cars. They are built to specification, much like your smartphone” and “In contrast, the Tesla model 3 uses a new 2170 cell which will be the battery that powers all future tesla models and even their home energy storage solutions.”

Can’t speak for the i3, but it appears that LG Chem is using the same pouch cell, at least dimensionally, for the Chevy Bolt, the Jaguar iPace, and possibly the Audi eTron. Chemistry could be different, though.

Regarding using the same 2170 cell in the Model 3 and Tesla’s home energy storage solutions….very likely not. Panasonic might use the same 2170 can, but the power/energy density requirements for EV batteries and home energy storage are very different, which drives the cell chemistry. Per Clean Energy Review, Tesla uses NMC for their Powerwall 2 modules. Home energy has fewer space and weight limitations plus does not have anywhere near the same power input or output density requirements. I believe Panasonic make separate production runs at the GF for the energy storage cells and the EV cells.

I might differ on the fact that the new 21 70s have more silicone in the anode. I swear I heard Jason Hughes saying that they backed off on the Silicon content after the 90 kilowatt-hour cells.

However I don’t have any concrete evidence of it.

If anyone has a source that can verify it please let us know

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4 months ago

antrik

Does that imply that the 100 kWh pack uses different cells than the 90 kWh one? I always assumed they are the same, since they have pretty much exactly the same per-cell capacity, and were released in pretty short succession… Either way, I think Jason would have to have some special insider source to make such a claim. The only mention I remember from Tesla (or any other official source) was a claim that they are using a tiny amount of silicon now, and intend to gradually increase it. I think that was not too long ago (less than two years?), most likely in the context of Gigafactory cells. That’s not to say the numbers in the video are any more reliable, though. I’m pretty sure they are just independent guesstimates. The “5%-15%” figure for silicon contents is not only very vague, but the higher end at least is also very implausible. 15% would mean more than half of the entire anode capacity would be provided by the silicon; and the whole thing would have some 50% volume expansion. That might be the case for the speciality cells I have seen somewhere that claim 4000 mAh, but only 50 cycles…… Read more »

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4 months ago

pjwood1

During the Q2 call, they talked about how rapidly chemistry can be changed on the lines, as a virtue of GF.

At some point, in the vid, I thought I read “$7.50 per pound, $3.41 per KG”. Not sure if different materials, or symbols got swapped.

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4 months ago

antrik

I don’t remember them talking specifically about rapidity of switching chemistries?… I just know they mentioned that they temporarily repurposed the line for storage cells to produce automotive cells instead… But I guess I might have missed something in all the mumbling 🙂

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4 months ago

antrik

Although I don’t remember specific sources of the top of my head, I think it’s official that Tesla’s storage products use NMC cells rather than NCA, or as good as official at any rate.

(Though that alone doesn’t explain the large capacity difference. I’m virtually certain they are also operated at lower voltages; and may also have other modifications to improve cycle life at the cost of some capacity.)

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4 months ago

antrik

LG indeed seems to be selling the same cell format to different clients (in fact someone dug up some sellers offering these cells independently…) — though that doesn’t strictly rule out the possibility that they were originally designed for the Bolt specifically, and they just reused the design… I’m not aware of any actual standards for pouch cells. The prismatic BEV2 cells used by BMW (as well as the PHEV2 format used by VW, both in actual PHEV and in BEV variants…) are a very different story though. The format is standardised by VDA, and available from multiple cell makers, sometimes at the same capacities. (Not sure whether they can be considered off-the-shelf though, since I have yet to see any actual catalogue for them…) BTW, the implication in the video that large pouch cells offer better packaging, and Tesla only uses the tiny cylindrical cells for flexibility, is almost certainly wrong. While it’s true that Tesla gets more flexibility in scaling pack capacities (something I occasionally pointed out myself), that wouldn’t require quite as tiny cells. The cylindrical format offers other unique advantages beside flexibility; and pouch cells do not actually provide better pack-level density. While it might seem… Read more »

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4 months ago

Unplugged

I do know that the Volt and the Focus Electric were based on the same pack from LG. Now, the Volt, Bolt and Focus Electric cells are all made at the LG plant in Michigan.

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4 months ago

Don Zenga

So they are using some amount of graphite which is an isotope of Carbon.
Carbon is a widely available element and graphite is much cheaper than many other elements.

Hope these batteries find its way into Model-S/X and other upcoming vehicles and they finally hit the magic $500 / KWh # just like Solar PV panels found their magic $ 5/Watt.

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4 months ago

antrik

Almost all Li-Ion cells use graphite anodes. (LTO cells are the only exception I’m aware of.) Though the lithium metal anodes likely coming in a couple of years will obviously change that…

Batteries are already way below 500 $/kWh; in fact several makers (and especially Tesla) claim way below 200 $/kWh right now. 100 $/kWh seems to be generally considered the needed “magic” number for EV mass adoption…

Also don’t know why 5 $/W would be “magic” for PV. At that price, it was still far from competitive with fossil generators. Right now utility-scale PV is somewhere around 1 $/W.

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4 months ago

jamcl3

Graphite is an allotrope of carbon, not an isotope. But you are correct otherwise.

Some lithium ion battery manufacturers use hard carbon instead of graphite (EnerDel if I recall) for esoteric reasons.

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3 months ago

Doggydogworld

I’m pretty sure the original Roadster used LCO, not NCA.

I agree with HVACMAN the energy storage cells are different. Probably NMC, though I’ve never been able to confirm that. GF sources say Panasonic makes those cells on separate lines, though, and it takes a week or so to switch a line from making car cells to energy cells.

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4 months ago

George Bower

agreed Doggy I didn’t think the roadster batts were NCA either

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4 months ago

Domenick Yoney

I think you are right. I believe the original Roadster chemistry was LiCoO2.

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4 months ago

Tom

Yep

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4 months ago

antrik

Beside issues pointed out by others, the video and description have several more errors. NCA cells are not known for outstanding cycle life and power density (i.e. charging rates). While Tesla does pretty well on these scores due to their careful engineering, NMC is generally considered superior on both counts. The unique advantages of NCA are highest energy density, and lower cobalt contents compared to other high-capacity chemistries. The “stages” make no sense: what happened between 2012 and 2016? As far as I can tell, there are at least four distinct generations: the original Roadster (using LCO according to various sources, as others already pointed out); the original Model S (60 kWh and 85 kWh packs); Model X and newer Model S (90 kWh and 100 kWh packs); and now Model 3. How would it impact GM if other makers started buying cells from LG? Not at all. (Except they might get better prices for future contracts due to economy of scale…) GM made contracts with LG, and LG built out production capacity accordingly. When additional clients make contracts, LG will build out additional capacity accordingly. Aside from logistics advantages, some people pointed out that the real reason for the… Read more »

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4 months ago

Jerry

It was good until the pouch vs cell space needed comment. There is no reason standard pouch sizes can’t fit even more places than the 2170s can.
Even if not custom sizes are easy in these quantities , just move the cutting, sealing lines. I think pouch will rule in the end as inherently easier to cool, build them and far less parts.
On Tesla’s modules they make the lower range by putting fewer cells in the module. Trying to keep it all together shooting in the cells without crimping the cooling tubes loose because 35% of the cells are missing is likely why the module delay happened and why everyone is getting long range 3s.

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4 months ago

antrik

Do you realize how large automotive pouch cells are? They are *not* easy to fit in a given geometry. Even if you use a custom format for each specific vehicle (complicating mass manufacturing), you are still pretty constrained in terms of pack geometry, since all cells in the pack have to be the same size. Admittedly, that’s more important for retrofits — like those Kreisel Electric does, or Tesla did in the past — than for a clean-sheet skateboard design… Nevertheless, it’s a relevant design constraint. Also, contrary to popular belief, pouch cells are *not* easy to cool. They can only be cooled on the flat sides, which makes for poor heat transport inside the cell, since the heat has to pass through all the individual layers. Also, it’s not realistic to route active coolant along the flat side; so instead, passive heat conductive plates need to be put between the cells in the stack, and in turn attached to the active cooling lines. In cylindrical cells on the other hand, the metal can is directly connected to the electrodes, providing for good heat transfer for the entire cell; and the cells can be directly pressed against, or glued to… Read more »

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4 months ago

Raymond Ramirez

Tesla has excellent engineering, but weak delivery, as the Model S and now the Model 3 has several faults that lower its initial image as the “perfect EV car”. The Panasonic cells are glued together then a conductor is welded in parallel in 12 V packs at high amperage. There is no protection and weak insulation between cells, so if one cell explodes, the aluminum shrapnel takes out several of its neighboring cells, and adds to the fuel of the initiating fire. And this is why Model S packs can burst into flames, even without any impacts. Watch the videos of burning Tesla models and you can observe the “firecracker” effect of smaller explosions from addition cells.

So if Tesla wants to improve, they need redesigning and better cell insulation between the cells of their packs. That may reduce energy density and increase weight which reduces range, but all safety designs have been adding weight to modern cars and protecting occupants, especially in collisions. I prefer a heavier EV with lesser range than a potential firebomb under my feet!.

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4 months ago

antrik

12 V packs? No idea what you are talking about…

“Shrapnel” is nonsense. The fire spreads to neighbouring cells just like any fire spreads: through flames. And I don’t see how *any* of the EV battery architectures I’m familiar with could prevent that…

(You will be happy to hear though that the architecture of the Model 3 pack actually adds some thermal isolation between cells, which should slow, or maybe even stop propagation of fire…)

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4 months ago

Eva Glimsche

QM Programm / UN 38.3 Test
Unfortunately some important infos for the logistic of shipping a Tesla or a Tesla lithium ion battery were not given – some questions are therefore still left unanswered:
1. In order to ship a battery-powered vehicle internationally the battery needs to be manufactured according to the Quality Management System described in the transport regulations (Source e.g. ICAO TI, Part 2, 2;9.3.1 e)).
2. Also each non-prototype non small production series lithium ion battery needs to have successfully passed the UN Test Series 38.3.
3. A confirmation that the battery incorporates a safety venting device or is designed to preclude a violent rupture under normal conditions of carriage.
4. A confirmation that each battery is equipped with effective means as necessary to prevent dangerous reverse current flow.
Up until now we were unable to receive any of those infos from Tesla. So it would be great if in Part 2 of “Everything You Ever Wanted to Know About Tesla Batteries” you could answer those questions, too.

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3 months ago

William Baker

Are the gen one batteries as good as the gen 2 and 3 for longevity?
The new ones are just cheaper to build right?